Because... Why? Is the restriction at the valve, not the throttle body ... When forced.

In a week or two when it returns I will post before and after.

By the way, your videos are very inspiring.

basically since the air is presurized its being forced threw the opening.

anyways if u want to know if ur tb is to small in n/a form hook up a vacum gauge and go wot. as long as it gets to 0 vac its not to small , if u are seeing any vacum at wot then u know its a restriction

btw whats the size of the butterfly on the saturn tb?
we use single 48-52mm tb's on engines upto 3.6L of displacement without them being a restriction

A clarification , in case somebody cares, the throttle body, was originally from a Geo ? and is 52mm. It is a common upgrade, or was. When these cars were made, supposedly. If you look into a Saturn SL factory manual the LLO tb of that year are 45mm. Just so things match up and make sense.

taper can increase velocity and or smooth the incomming air.
on a tb i doubt it gives any noticeable increase , unless of course u have a tb that is horribly designed

when it comes to replacing a stock tb with a larger or bored out unit most ppl think they are feeling a hp increase , when in reality if u take the stock tb at 1/4 throttle opening and then the larger unit at the same throttle opening the larger tb will alow more air into the engine.

so u dont have to step on the gas as far to accelerate like u did with the small stock tb

go to large with a tb and the throttle becomes more of an off on switch

If you want to step up to larger throttle body, there are ways to keep them from becoming "twitchy" and from being like an off/on switch.

Check outthese Vortec t-bodies. As you can see there is a 1/2 moon shaped device that is specifically designed to prevent such scenarios. The Vortec 4.3 has a bigger 1/2 moon device than teh Vortec 305/350 t-bodies.
The 305/350 t-bodies are 75mm, IIRC the 4.3 t-bodies are smaller at 65mm, but I may be confusing t-body size with MAF sizes.

Forced induction is very sensitive to air restriction on such through t-bodies, but not as much with blow through t-bodies. If this setup is a suck through t-body mods or upsizing can make dramatc diferences.

I upgraded the fuel system. larger injectors, pump, and higher fuel psi. This is new stuff to me so I am playing it real safe watching the wide band. Currently I am looking into a piggy back injector enrichment system for the turbo to replace the rrfpr. There is also a AFC hack that I am looking into for the Honda vehicle. The Saturn I have not gotten word back on what the owner wants to do, and still waiting for the turnaround on the TB from VMS.

I am open to suggestions. How would you add fuel for the boost, on a obd2 system? It has to stay in closed loop part throttle boost. I

I would enjoy getting to a track again at some point. According to the torque software that is based off of the vss for distance, the twin cam was in the high 14's with some boost. Like a estimate 180-190 whp.

I like to work on the RWD vehicles but there are so few to find. You get bored and end up with a 4 banger.

I never realized that the larger injector size you go the worse it idles...kind of like a cam without the lope. Could be that is the untuned condition. Gimme a some time, Ill get the bugs worked out.

I upgraded the fuel system. larger injectors, pump, and higher fuel psi. This is new stuff to me so I am playing it real safe watching the wide band. Currently I am looking into a piggy back injector enrichment system for the turbo to replace the rrfpr. There is also a AFC hack that I am looking into for the Honda vehicle. The Saturn I have not gotten word back on what the owner wants to do, and still waiting for the turnaround on the TB from VMS.

I am open to suggestions. How would you add fuel for the boost, on a obd2 system? It has to stay in closed loop part throttle boost. I

I would enjoy getting to a track again at some point. According to the torque software that is based off of the vss for distance, the twin cam was in the high 14's with some boost. Like a estimate 180-190 whp.

I like to work on the RWD vehicles but there are so few to find. You get bored and end up with a 4 banger.

I never realized that the larger injector size you go the worse it idles...kind of like a cam without the lope. Could be that is the untuned condition. Gimme a some time, Ill get the bugs worked out.

edit- the ones pictured came from maxbore.

First off, what in the hell is part throttle boost?

Secondly, without retuning for larger injectors you're getting that cam sound because your giving it way too much fuel at idle, and if they are WAY over the stock size they can only open and close so fast so you'll never get a perfect idle even with tuning.

until you get it tuned for the injectors I would drive it as little as possible.

From the little research I did most turbo SC2 saturns are running megasquirt, which is a great cheap EFI system, and NOT OBDII compatible.

Tipping in to load conditions pops a wrench it goes lean and back into open loop. I read somewhere this is because the map can only read so much boost. So online they say you can get a one way valve that fits in front of the map to keep it from sensing positive pressure. Possible this is not the case, and there is something else wrong.

Substitute the word load for boost . Manifold pressure is building faster than normal while increasing load. It goes lean everytime. I really am not sure why.

Megasquirt does get good recommendations but it is not street legal.

Using RC 310cc saturated type injectors. The calculator suggests should be right on a 1.9L at 180-200whp.

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